1. Field of the Invention
The present invention generally relates to a bird feeder apparatus. More particularly, the present invention relates to a bird feeder apparatus designed to provide a readily available source of feed to birds, while further functioning to prevent other small animals, such as squirrels and raccoons, from gaining access to the bird feed.
2. Description of the Prior Art
The study of birds is formally referred to as ornithology and within the broad compass of ornithologists is found a remarkable array of bird enthusiasts. They range from the person who notices which bird species visit the garden birdbath to the computer buff trying to mathematically describe the fate of some host population subject to the parasitic attentions of cowbirds or cuckoos. To be sure, bird enthusiasts are well-numbered and these numbers continue to grow. Accordingly, markets continue to develop in an effort to cater to the growing needs and desires of the bird enthusiast population. In this last regard, it is noted that there are two avenues by which the typical bird lover or ornithologist pursues his or her study of birds. Either the bird enthusiast will travel to the ecosystem in which the various bird species live or the bird enthusiast will attempt to lure or attract various bird species to the “ecosystem” in which the bird enthusiast lives. It is with this latter trend in mind that the present invention is proposed. In other words, a growing desire among bird enthusiasts or bird watchers is to attract various species of birds to the vicinity of the residential abode or similar other setting in which the watcher spends a considerable amount of time.
The most successful way of attracting birds and increasing their number in a given setting is to satisfy their most basic needs—good food, nesting sites and water. In this regard, the bird feeder is useful in any attempt to attract birds to a given setting. Providing a source of food, however, has a tendency to attract not only birds, but other wildlife, such as squirrels and raccoons. Given the uncanny ability for squirrels and the like to deplete stores of bird food from bird feeders, a number of attempts have been made to develop an effective anti-squirrel or squirrel proof bird feeder. Thus, anti-squirrel bird feeders are known in the prior art, some of which are described hereinafter.
U.S. Pat. No. 5,163,382 ('382 patent), which issued to Morrison, discloses a Bird Feeder Apparatus. The '382 patent teaches a bird feeder arranged to discourage squirrels from access to food within the feeder comprising a first housing reciprocatingly receiving an second housing, with the first housing including side wall openings and the second housing including side wall openings aligned in a first position and displaced in a second position when a squirrel alights upon a top wall of the first housing projecting the second housing within the first housing preventing access of the squirrel to food components within the second housing.
U.S. Pat. No. 5,195,459 ('459 patent), which issued to Ancketill, discloses a Bird Feeder. The '459 patent teaches a bird feeder comprising a food holder and shroud which is biased in an open position by a spring. When an animal such as a squirrel not intended to feed from the bird feeder lands on the shroud or a roof portion of the shroud, the weight of the animal causes the shroud to descend against the biasing action of the spring. The shroud closes the food holder thereby preventing the animal from gaining access to the food.
U.S. Pat. No. 5,720,238 ('238 patent), which issued to Drakos, discloses a Spring Operated Squirrel Proof Bird Feeder. The '238 patent teaches a squirrel proof bird feeder comprising an inner and outer housing with the inner housing fixed vertically and with the outer housing telescopically received thereabout and moveable between upper and lower positions. The housings have openings which are aligned and which provide through openings serving as feed ports in the upper position of the outer housing. In the lower position of the outer housing, the openings are misaligned and close the feed ports. The outer housing is also provided with springs biasing the same toward the upper position but allowing the housing to move downwardly to the lower position under the weight of the squirrel.
U.S. Pat. No. 5,964,183 ('183 patent), which issued to Czipri, discloses a Bird Feeder. The '183 Patent teaches a bird feeder having an inner feed containing tube with a removable top, fixed bottom and feed access openings therein, an outer tube shrouding the inner tube and having feed access openings therein and an upper and lower position. In the upper position the feed access openings in the inner and outer tubes are aligned and when the outer tube moves downwardly relative to the outer tube the access openings are closed. A lever is pivotally connected to the fixed bottom and operatively connected to the outer tube. A biasing element urges the lever to pivot in a direction to move the outer member to its upper position.
U.S. Pat. No. 6,119,627 ('627 patent), which issued to Banyas et al., discloses a Rodent Repelling Bird Feeder. The '627 patent teaches a cylindrical rodent repelling bird feeder having an annular perch around the feeder and an electric motor geared to the perch. The perch is coupled to the electric motor and the electric motor is reciprocatively mounted in the bird feeder so that when a rodent of excessive weight alights upon the perch the motor is pulled against a resistance spring and a switch is caused to close, thereby engaging the motor which rotates the perch to dislodge the rodent therefrom.
U.S. Pat. No. 6,543,384 ('384 patent), which issued to Cote, discloses a Bird Feeder Having Lower Movable Shroud. The '384 patent teaches a squirrel proof bird feeder wherein there is provided a lower movable shroud which extends about a lower portion of the feed container having feed access openings therein, a spring member biasing the shroud to a position wherein feed container access openings and shroud access openings are substantially aligned while permitting the shroud access opening to move out of alignment with the feed container access opening when a predetermined weight is placed on the shroud.
From a review of these prior art disclosures and from a general consideration of other well known prior art teachings, it will be seen that most prior art anti-squirrel bird feeder designs incorporate either a linear closure mechanism based on a linear spring or a nonlinear closure mechanism based on a teeter-totter, mass balance. It will be seen that none of the prior art disclosures teach a non-linear, four-bar closure mechanism, which four-bar closure is of critical importance to the present invention and described in more detail hereinafter.
Generally, nonlinear closure mechanisms are preferable to linear closure mechanisms for anti-squirrel bird feeder applications. A linear mechanism closes linearly with load, i.e., closure is proportional to load; therefore, a linear closure mechanism is usually set heavy, i.e., set to reach full closure at a load equal to the weight of an adult squirrel, for example. The reason for a heavy setting is that a light setting can result in significant closure when only a few birds are feeding, restricting access to seed, thereby diminishing the utility of the feeder. The unsatisfactory consequence of a heavy setting, however, is that an immature or lightweight squirrel could defeat the closure mechanism. These properties of the linear mechanism are not present in nonlinear mechanisms making nonlinear mechanisms more desirable.
A nonlinear closure mechanism usually closes minimally until a critical point is reached when subsequently its closure occurs immediately and fully; therefore, it is far more desirable than a linear closure mechanism. The four-bar mechanism of the present invention is superior to a teeter-totter, mass balance type mechanism in that its action is less susceptible to adverse frictional effects that inhibit/prevent immediate and full closure; therefore, a four-bar mechanism is more robust as explained in the following paragraphs.
The four-bar mechanism's stability is based in geometry rather than mass balance. The unequilibrated moment about the pivot pin of a teeter-totter, mass balance mechanism is a function of the small difference between the squirrel's mass and the set mass; therefore a small amount of pivot pin friction could defeat the teeter-totter, mass balance mechanism by precluding closure. Noteworthy is that at least one teeter-totter design judged “undefeatable” has indeed been defeated by squirrels. Video taped documentation evidences two squirrels working in unison to defeat the teeter-totter type design. The reader should reference: “Daylight Robbery II”, which aired in the United States on the Discovery Channel on Nov. 26, 1995, having been produced by the British Broadcasting Corporation Worldwide Limited in 1995 as presented by Dr. Jessica Holm. One squirrel was observed to counterbalance the other preventing closure of the gate to the feeder's seed. Subsequently, one or the other of the two consumed the feeder's seed. Such cooperative action cannot defeat the four-bar mechanism of the present invention. The frictional moment about a pivot pin of the four-bar mechanism is acted upon by a function of structure's dead load plus its live load; therefore a four-bar mechanism can accommodate much larger pivot pin friction without significant adverse effects. Recovery of the four-bar mechanism is also more robust than the teeter-totter, mass balance mechanism because it is less affected by friction. Recovery at closure is based in geometry not mass balance, as the following specifications will clarify. Another advantage of the four-bar mechanism is that, unlike a teeter-totter, mass balance mechanism, the four-bar mechanism is not limited in feeder and closure design, which is usually bound to rectangular box-like structure.